Category: unknown brand HWC

We were a rebuild (Brickworks Lane) and had a brand new cylinder. We went through three elements (One every three months). They finally replaced it with a titanium element on Christmas Eve! This seems to have fixed the problem.

This is due to the stainless steel, not the water. This is the point of stainless steel, it is very resistant to corrosion but if it touches virtually any other metal, other than stainless steel (the same type of stainless steel mind you) then it will cause the other metal to corrode faster. This is when they are in physical contact and wet (the water acts as an electrolyte).

This is why you should never have copper, galvanised steel or mild steel in contact with stainless steel when they can get wet i.e. outdoors or in plumbing systems. If they are needed to be together, the two different metals need to be separated by an insulator such as plastic or rubber.

Many hot water cylinder elements are made with an Inconel sheath (a nickel alloy) which would be ok for a copper cylinder. They should really have a stainless steel sheath as the Inconel sheath is good for high temperatures but this not necessary for a hot water cylinder.

The Centaurus/Huntsbury water supply is definitely different to other parts of ChCh. We get lime scale in our kettle, which I have never had in any other suburbs.

We’re down Bowenvale and had our new hot water cylinder replaced a couple of years ago. At the second failure we installed a sacrificial anode and haven’t had a problem since. Probably something that needs to be done as a matter of course. I understand the old copper cylinders are OK but the stainless steel ones just corrode.

We did have gas and decided to go solar. For this we needed to put in a cylinder and that’s when the problems started. First we had to replace the element after about year and then the whole cylinder and the element after another 6 months or so. This is when the sacrificial anode was added and that seems to be working.

We live in St Martins and built our house in 2009. We have just had our hot water cylinder replaced as the original one (6 years old) has corroded and was leaking. We now have a sacrificial anode which will hopefully prevent the new tank corroding.
Looking at the amount of corrosion in the tank, I suspect we have the same problem with the water here as you have in Cashmere.
Caroline